Method of coating a catalyst to a support for use in acrolein oxidation

ABSTRACT

A method of coating a catalyst to a support for use in acrolein oxidation reaction. Metallic salt components of the catalyst including molybdate, vanadate and tungstate are dissolved in a liquid to form a suspension of particles of the catalyst. The precipitation of the catalyst particles is controlled by homogenizing the catalyst particles suspended in the liquid. The phase separation between the catalyst particles and the liquid can be substantially slowed down by the homogenization. Then the catalyst is coated on an inert support by applying the suspension of the catalyst particles to the support. In the suspension, the total weight of water is about 0.8 to about 5 times of the total weight of the metallic salts in the catalyst. This method of preparing suspension minimizes the amount of the liquid required to dissolve the metallic salts, which reduces the amount of time and energy to be used in evaporating the liquid from the suspension. Additionally, in obtaining catalyst from the suspension prepared by this method, it is possible to avoid the deterioration of the catalytic performance since less heat is required to evaporate the water.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 09/158,877, filed Sep. 23, 1998, U.S. Pat. No. 6,171,998B1,issued Jan. 9, 2001.

BACKGROUND OF THE INVENTION

1. Field of The Invention

The present invention relates to a catalyst for acrolein oxidation, moreparticularly, to production of the catalyst containing molybdenum,vanadium, and tungsten as essential components.

2. Description of the Related Technology

In producing of acrylic acid, oxidation reactions of acrolein withoxygen molecules in the presence of a catalyst have been widely used.The preparation of the catalyst has been researched to obtain a highyield of the acrylic acid, which are primarily directed to thecomponents of the catalyst and the composition thereof. Also, somemethods of producing a carrier-retained catalyst have been provided inthe prior art.

Japanese Patent Application Laid-Open Nos. Showa 49-117419, Showa58-166939, and Showa 64-63543, and European Patent Application Laid-OpenNo. 293,859/1988 disclose methods for producing a carrier-retainedcatalyst, in which aqueous solutions of metallic salts of catalystcomponents are mixed and coprecipitated to produce a suspension of acatalyst. An inert carrier, which has a small surface area and a largeaperture ratio, such as round or cylindrical silicon carbide, silica,and silica-alumina, is added to the suspension, and water is evaporatedby heating the suspension with agitation to produce a catalyst retainedwithin the structure of the inert carrier.

Further, in U.S. Pat. Nos. 4,157,987, 4,259,211 and 4,892,856; andKorean Patent Application Laid-Open No. 7409/1993, a suspension of acatalyst is heated to evaporate water while being stirred. Anhydroussolid of the catalyst is obtained and is ground to powder, which iscoated on an inert carrier, such as alundum, by using a coater.

The inert carriers retain the catalyst in their structures and preventthe release of the catalyst at a time. Accordingly, occurrence ofexcessive oxidation reactions, which may be caused by supply of abundantcatalyst, can be avoided. Also, the inert carrier functions as heatbuffer by absorbing the heat generated during the oxidation reaction.

Korean Patent Application Laid-Open No. 7409/1993 and U.S. Pat. No.4,892,856/1990 disclose that physical properties, such as non-surfacearea, pore volume, and pore diameter distribution, vary in the catalystsprepared even from the identical component metallic salts andcomposition thereof. The variance in the physical properties ofcatalysts results in the variance in the catalytic performance ofcatalysts, i.e., the acrolein turnover ratio and acrylic acid yield.This means the physical properties and accordingly the catalyticperformance of the catalysts change, depending on the preparationalmanipulations as well as the conditions thereof, which also causes thelack of reproducibility in preparing the catalyst. In addition, thesevariances of the catalytic performance sometimes exceed those by thechanges in the components and the composition of the catalyst.

However, there has not yet been a report, which satisfactorily addressesthat the physical properties and accordingly catalytic performance of acatalyst change, depending on the process of producing the catalystincluding the preparation of a suspension or powder therefrom.

Meantime, in the preparation of the aqueous solution of metallic salts,an excessive amount of water is required to dissolve some metallic saltshaving low solubility in water, such as ammonium metavanadate andammonium paratungstate. The amount of water in the suspension of thecatalyst is from about 5 to about 10 times by weight of the salts. Thesolubility improves when the temperature of water increases, but heatingof the aqueous solution of the salts deteriorates the catalyticperformance.

The water used to prepare the suspension has to be completely removed toform a powder catalyst. Accordingly, the amount of energy and timerequired to remove the water has a direct relation to the amount ofwater used. Further, in the case where an inert carrier is added to thesuspension to produce a carrier-retained catalyst, additional time isrequired to remove the water within the carrier structure.

SUMMARY OF THE INVENTION

The present invention provides a method of coating a catalyst to asupport. The method comprises dissolving salts of metallic components ofa catalyst in liquid to form a suspension of particles of the catalyst;controlling a speed of precipitation of the catalyst particles in theliquid; and coating the catalyst on an inert support by applying thesuspension of the catalyst particles to the support. The salts ofmetallic components comprising molybdenum, tungsten, and vanadium.

The controlling the speed of the precipitation comprises homogenizingthe catalyst particles suspended in the liquid so that phase separationbetween the catalyst particles and the liquid can be substantiallyslowed down. The catalyst particles are homogenized by at least oneselected from the group consisting of ball mill, attrition mill, dynamomill, homogenizer, and supersonic homogenizer. Most of the catalystparticles are homogenized to a size of less than about 10 microns indiameter. The homogenization of the suspension step is conducted eitherduring or after the preparation of the suspension.

The catalyst is coated by spraying the suspension to the support andsimultaneously drying the support. The catalyst particles are coated byone of the group consisting of a rotatory coater, a sugar coater, acentrifugal flow coater, and a pherudizer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The inventors of the present invention have discovered that propertiesof a catalyst suspended in the water solution change when the suspensionof the catalyst is heated to a high temperature. In addition, theproperties of the catalyst change when the catalyst suspension is heatedfor a long period of time. The property changes cause deterioration ofthe catalytic activity or performance later. This also leads to areduction in the reproducibility of the catalyst, and the performance ofthe powder catalyst or the carrier-retained catalyst becomes hard tocontrol.

However, as noted above in the background of the invention supra, toreduce the heat application to the catalyst suspension, it is requiredto minimize the amount of water needed to dissolve the metallic salts.In this regard, the inventors also have discovered that some metallicsalts dissolve in water better when they dissolve in an aqueous solutionmixture of other metallic salts than when they dissolve in waterseparately. Specifically, molybdate, vanadate and tungstate, which areessential to produce a highly active catalyst, dissolve in water andform a concentrated aqueous solution mixture with higher solubility thaneach of the separate aqueous solutions thereof.

In accordance with one aspect of the present invention, first metallicsalt components of the catalyst, which have low water-solubility, aredissolved together in water to form an aqueous solution of the salts.Each metallic salt dissolves in the aqueous solution more than itdissolves in water alone. The remaining metallic salt components of thecatalyst, which have high water-solubility, or the aqueous solutionthereof are added to the aqueous solution prepared above to form acatalyst suspension. The amount of water required to prepare thesuspension of the catalyst can be drastically reduced, which in turnreduces the time and energy in removing the water to produce a powdercatalyst in the following step. Further, since less heat is required toevaporate the water from the suspension, the property changes of thecatalyst due to the heat application for a long time, which may causethe deterioration of the catalytic performance, do not appear.

In the preparation of a catalyst suspension, molybdate, vanadate andtungstate are dissolved in water at a temperature of at least about 90°C., preferably in boiling water. Once they are completely dissolved, theaqueous solution is cooled to a temperature between about 60° C. andabout 80° C. The remaining salts of metal A and metal B, or an aqueoussolution of these metallic salts, are added to produce a catalystsuspension. Here, metal A is at least one element selected from thegroup consisting of iron, copper, bismuth, chromium, tin, antimony,nickel, cobalt, manganese, cerium and thallium, and metal B is at leastone element selected from the group consisting of an alkali metal and analkali earth metal. The total amount of water with reference to theamount of the metallic salt components of the catalyst by weight isabout 0.8 to about 5 times, and preferably about 1 to about 2 times.

The water is evaporated from the suspension by heating and an anhydroussolid of the catalyst remains. The solid is ground and dried to obtain apowder catalyst, which is represented by the Chemical Formula I below.The powder catalyst is finally coated on an inert carrier, such asalundum, to produce a carrier-retained catalyst. Alternatively, an inertcarrier, such as round or cylindrical silicon carbide, silica, andsilica-alumina, is added to the catalyst suspension, and the water isevaporated by heating the suspension with the inert carrier to produce acatalyst retained within the structure of the inert carrier.

Mo_(a)W_(b)V_(c)A_(d)B_(e)O_(x)  [Chemical Formula 1]

Wherein, a, b, c, d, e and x respectively indicate the atomic ratio forMo, W, V, A, B and O, in which when a=10, then b=1.5 to 4, c=1 to 5, d=1to 4, and e=0 to 2 and x is determined according to oxidation states ofthe other elements.

The performance of the dried catalyst powder is superior to that of thedried catalyst produced by using a large amount of water in thepreparation of a catalyst suspension, which is heated at an identicaltemperature as above and for a long period of time. Ultimately, theperformance of the carrier-retained catalysts is also improved.

In accordance with another aspect of the present invention, provided isan alternative method of producing a carrier-retained catalyst. Thecatalyst suspension is sprayed onto an inert carrier, while it is driedby heated air.

A catalytic suspension is prepared by the above method in accordancewith one aspect of the present invention or any other method known inthe art. However, when a catalyst suspension is prepared by mixing andstirring two different aqueous solutions, in which one has the metalliccomponents as cation and the other has the metallic components as anion,the catalyst particles promptly settle down. When the agitation isdiscontinued, the catalyst particles precipitate and form phaseseparation from water.

When the catalyst suspension is sprayed on the carriers to producecarrier-retained catalysts, it is difficult to obtain homogeneouscoating if the catalyst particles settle downward and phase separationoccurs. In addition, if the settling speed of the particles is fast, thetransfer and spray of the suspension by pumping is not possible. Theinhomogeneity of the suspension may also affect the catalyticperformance and the reproducibility of the catalyst in producing thecarrier-retained catalyst.

According to the present invention, the crystal particles suspended areadvantageously splitter or ground into smaller particles to maintain thehomogeneous suspension of the catalyst. At least one of ball mill,attrition mill, dynamo mill, homogenizer, or supersonic homogenizer canbe advantageously used to split or ground the catalyst particles withour without agitation. Any conventional method for making particle sizesmaller can also be used.

The catalyst particles are split or ground so that the suspendedparticles can be transferred and sprayed through a nozzle without beingstuck. The size of the particles in the suspension advantageously hasthe diameter of less than about 10 microns. The particles of these sizessettle slowly and do not cause the phase separation even at slowagitation, which makes the catalyst suspension homogeneous. As a result,the settling speed of the precipitate is controlled so that spraycoating of the catalyst suspension can be possible. The suspension, inwhich the particle sizes get smaller, is sprayed onto inert carriers andsimultaneously dried with heated air to produce the carrier-retainedcatalyst.

The splitting or grinding the particles can be made after the completeproduction of the catalyst particle suspension from the aqueous solutionof the metallic salt components of the catalyst. This operation can alsobe made during the production of the catalyst particle suspension, andadvantageously simultaneously with the production of the catalystparticles.

According to the present invention, the inert carrier can be at leastone from the group consisting of alundum, silica-alumina, and siliconcarbide. Advantageously, the catalyst can also be coated by a rotatorysugar coater, centrifugal flow coater, or a pherudizer.

According to the present invention, for the metals of molybdenum,vanadium, and tungsten, any salts can be advantageously used. For thoseof metals A and B, a nitrate, acetate, carbonate, and organate can beused, but chloride or sulfate of them is not preferable.

A gas phase oxidation reaction in the presence of the carrier-retainedcatalyst produced according to the present invention is carried out inthe manner known in the art. For example, 1 to 10 volume % of acrolein,1 to 15 volume % of oxygen molecules, 5 to 60 volume % of aqueous vapor,and 20 to 80 volume % of inert gas (totally 100%) react in the presenceof the catalyst at a temperature of 200 to 350° C. between atmosphericpressure and 3 atmospheric pressures, at a space velocity (STP) of 500to 4,000 hr⁻¹.

The present invention will now be further described by the followingexamples:

EXAMPLE 1

950 ml of distilled water was heated to boil. 120 g of ammoniumparatungstate, 405 g of ammonium molybdate, and 94 g of ammoniummetavanadate were added in order and stirred until they are completelydissolved, while the mixture was being heated to boil. An aqueoussolution prepared by dissolving 111 g of copper nitrate and 39 g ofstrontium nitrate in 50 ml of water was added to the above ammonium saltaqueous solution to form a suspension. The ratio of the amounts of waterto metallic salt in the solution by weight was 1.3:1. The suspension wasstirred and heated to evaporate the water and obtain an anhydrous solid,while the temperature was maintained to 70° C. The anhydrous solid wasdried at 120° C., a part of which was ground to obtain a powder catalystwith 80—120 mesh particle sizes. The powder catalyst was coated ontoalundum having a diameter of {fraction (3/16)} of an inch by using wateras a binder. The carrier-coated catalyst was dried at 120° C. andsintered for 5 hours at 400° C. while fresh air was supplied. After thesintering, the catalyst powder was 30 wt. %, and the composition of thecomponents except for the oxygen was Mo₁₀W₂V_(3.5)Cu₂Sr_(0.8).

Comparative Example 1

Added to 4300 ml of distilled water heated to 80° C. were, in order, 120g of ammonium paratungstate, 405 g of ammonium molybdate, and 94 g ofammonium metavanadate. The mixture was stirred until all the metallicsalts were dissolved. An aqueous solution prepared by dissolving 111 gof copper nitrate and 39 g of strontium nitrate in 300 ml of water wasmixed with the above ammonium salt aqueous solution. The ratio of theamounts of water to metallic salt in the solution by weight was 6:1.This suspension was stirred and heated to a temperature between 80° C.and 85° C. to evaporate the water and obtain an anhydrous solid. Theanhydrous solid was dried at 120° C., a part of which was ground toobtain a powder catalyst with 80-120 mesh particle sizes. The powdercatalyst was then coated, by using water as a binder, onto alundumhaving a diameter of {fraction (3/16)} of an inch. The carrier-coatedcatalyst was dried at 120° C. and sintered for 5 hours at 400° C., whilefresh air was supplied. After the sintering, the catalyst powder was 30wt. %, and the composition of the components except for oxygen, wasMo₁₀W₂V_(3.5)Cu₂Sr_(0.8).

Comparative Example 2

The same experiment as in Comparative Example 1 was repeated except thatthe suspension was stirred and heated to a temperature between 90° C.and 95° C. to evaporate the water and obtain an anhydrous solid. Thecatalyst powder was 25 wt. %, and the composition of the elements,without oxygen, was Mo₁₀W₂V_(3.5)Cu₂Sr_(0.8).

EXAMPLE 2

100 ml of distilled water was stirred and heated to boil. 120 g ofammonium paratungstate, 405 g of ammonium molybdate, and 94 g ofammonium metavanadate were added in order and stirred until they arecompletely dissolved, while the mixture was being heated to boil. Anaqueous solution prepared by dissolving 100 g of copper nitrate, 18.6 gof iron nitrate, 24.4 g of strontium nitrate, and 1.2 g of potassiumnitrate in 75 ml of water was added to the above ammonium salt aqueoussolution to form a suspension. The ratio of the amounts of water tometallic salt in the solution by weight was 1.5:1. A portion of thissuspension was charged in an evaporator maintained at a temperature of70 to 75° C., and 1000 ml of silica-alpha alumina carrier particles (SA5218 of Norton Corp.), having a diameter of 5 mm and preheated tobetween 70 and 75° C., was added thereto. The mixture was maintained ata temperature between 70 to 75° C. while being stirred, and the waterwas evaporated therefrom, thereby obtaining an anhydrous solid. Theanhydrous solid was then combusted for 5 hours at 400° C. to produce acatalyst. Here, active catalyst components occupied 30% of a totalcarrier catalyst weight.

Comparative Example 3

3600 ml of distilled water was stirred and heated to boil. 120 g ofammonium paratungstate, 405 g of ammonium molybdate, and 94 g ofammonium metavanadate were added in order and stirred until they arecompletely dissolved, while the mixture was being heated to boil. Anaqueous solution prepared by dissolving 100 g of copper nitrate, 18.6 gof iron nitrate, 24.4 g of strontium nitrate, and 1.2 g of potassiumnitrate in 250 ml of water was added to the above ammonium salt aqueoussolution to form a suspension. The ratio of the amounts of water tometallic salt in the solution by weight was 5:1.

A portion of this suspension was charged in an evaporator maintained ata temperature of 80 to 85° C., and 1000 ml of silica-alpha aluminacarrier particles (SA 5218 of Norton Corp.), having a diameter of 5 mmand preheated to over 80° C., was added thereto. The mixture wasmaintained at a temperature between 80 to 85° C. while being stirred,and the water was evaporated therefrom, thereby obtaining an anhydroussolid. The anhydrous solid was then combusted for 5 hours at 400° C. toproduce a catalyst. Here, active catalyst components occupied 25% of atotal carrier catalyst weight.

Comparative Example 4

The same experiment as in Comparative Example 3 was repeated except thatthe temperature of the suspension was maintained and the carrierparticles was preheated was all between 90° C. and 95° C. to evaporatethe water and obtain an anhydrous solid. Here, the active catalystcomponents occupied 30% of the total carrier catalyst weight.

EXAMPLE 3

28.2 l of distilled water was added to a 50 l glass reactor, in which aconventional stirrer and homogenizer are installed. The water was heatedto a boil. While maintaining the boiling state of the water, added tothe same, in order, were 3,000 g of ammonium paratungstate, 10,125 g ofammonium molybdate, and 2,350 g of ammonium metavanadate, and themixture was stirred until all the metallic salts were dissolved. Whilerotating a rotor of the homogenizer at 4,000 rpm, an aqueous solutionprepared by dissolving 2,755 g of copper nitrate and 975 g of strontiumnitrate in 2.6 l of water was mixed with the above ammonium salt aqueoussolution. The homogenizer remained operating for 30 minutes after theabove two aqueous solutions were completely mixed. A suspension wasextracted, and the particle size of a precipitate was measured. Here,over 70% of the precipitate had a particle size of about 10 microns, theaverage particle size was 45 microns, and no particle size over 80microns was discovered.

The suspension produced as in the above process was sprayed ontoaldundum, having a diameter of {fraction (3/16)} of an inch, of a sugarcoater through a spray nozzle. Simultaneously, the aldundum was driedwith air heated to 90° C., thereby completing the coating on alundum.The carrier-retained catalyst was dried at 120° C. and sintered for 5hours at 400° C. while fresh air was supplied. After the sintering, thecarrier and catalyst powder were 30 wt. %. A composition of thecomponent except for oxygen was Mo₁₀W₂V_(3.5)Cu₂Sr_(0.8).

Comparative Example 5

A suspension was produced identically as in Example 3 except that only astirrer, and no homogenizer, was used. When stirring was discontinued,the precipitate quickly settled. When measured, over 30% of theprecipitate had a particle size exceeding 100 microns. This suspensionwas quickly stirred, and coating on a carrier was attempted. However,the suspension became clogged in the pump and transfer pipes, making thecoating operation impossible to perform.

EXAMPLE 4

Using both a stirrer and a homogenizer, the particle size of theprecipitate in the suspension of Comparative Example 5 was reduced.According to the results of a particle size analyzer, 60% of theprecipitate had an average particle size of 22 microns, while theremaining 40% of the precipitate had an average particle size of 60microns, with less than 5% of the precipitate having a particle size ofbetween 80 and 90 microns. Using this suspension, a carrier catalyst wasproduced identically as in Example 1. Further, no clogging in the pump,transfer pipes, or the spray nozzle occurred, and the composition of theelement without oxygen was Mo₁₀W₂V_(3.5)Cu₂Sr_(0.8).

EXAMPLE 5

22.4 l of distilled water was heated to a boil while being stirred.While maintaining the boiling state of the water, added to the same, inorder, were 1800 g of ammonium paratungstate, 6075 g of ammoniummolybdate, and 1410 g of ammonium metavanadate, and the mixture wasstirred until all the chemicals dissolved. An aqueous solution, whichwas prepared by dissolving 1500 g of copper nitrate, 279 g of ironnitrate, 366 g of strontium nitrate, and 18 g of potassium nitrate in2.25 l of water, was mixed with the above ammonium salt aqueoussolution. A homogenizer was operated at 4000 rpm and particles of theprecipitate were ground as in Example 3. The resulting suspension wasthen placed in a sugar coater and coated on 5 mm Norton Corp. SA 5218silica-alpha alumina carrier particles through a spray nozzle.Concurrently with this process, the suspension was dried using heatedair, thereby obtaining a carrier-retained catalyst. The final catalystwas obtained by using the drying and sintering method of Examples 3 and4. The composition of the element, without oxygen, wasMo₁₀W₂V_(3.5)Cu_(1.8)Fe_(0.2)Sr_(0.5)K_(0.05).

Test Example: Catalyst Activation Test

A catalyst activation test was conducted for the catalysts produced inthe above examples and comparative examples. 70 g of the catalystproduced in each example was place in a ¾-inch steel reaction tube,which is surrounded by 3 electric furnaces. A mixture of 6.5 volume % ofacrolein, 13 volume % of oxygen, 70.5 volume % of nitrogen, and 10volume % of water vapor was introduced into a reactor at atmosphericpressure. The temperature of the reactor was set at 260° C. for thecatalysts produced in Examples 1 and 2, Comparative Examples 1 to 4, andat 255° C. for the catalysts produced in Examples 3 to 5, andComparative Example 5. At a space velocity of 1500 hr⁻¹, the reactiontest was performed. After 72 hours of reaction, the composition of theproduced material was analyzed to obtain the turnover ratio of acroleinand the acrolein yield in a single flow. The results of the test appearin Table 1 below.

In the present invention, the turnover ratio and the yield in a singleflow were determined by the following mathematical formulas,respectively.

Turnover ratio (%)=[The number of moles of reacted acrolein]÷[The numberof moles of charged acrolein×100]  [Mathematical Formula 1]

 Yield in a single flow(%)=[The number of moles of producedacrolein]÷[The number of moles of charged acrylicacid×100]  [Mathematical Formula 2]

TABLE 1 Water to Acro- A- metallic lein crylic salt by Heating turn-Acid Mo W V A B weight Temp. over Yield Ex. 1 10 2 3.5 Cu 2 Sr 0.8 1.3:170 98 94.1 Com. 10 2 3.5 Cu 2 Sr 0.8   6:1 80 93 88.5 Ex. 1 Com. 10 23.5 Cu 2 Sr 0.8   6:1 90 89 86.3 Ex. 2 Ex. 2 10 2 3.8 Cu 1.8 Sr 0.51.5:1 70 96 93.3 Fe 0.2 K 0.05 Com. 10 2 3.8 Cu 1.8 Sr 0.5   5:1 80 9087.3 Ex. 3 Fe 0.2 K 0.05 Com. 10 2 3.8 Cu 1.8 Sr 0.5   5:1 90 85 82.5Ex. 4 Fe 0.2 K 0.05 Ex. 3 10 2 3.5 Cu 2 Sr 0.8 1.6:1 — 98.8 94.2 Com. 102 3.5 Cu 2 Sr 0.8 1.6:1 — —* —* Ex. 5 Ex. 4 10 2 3.8 Cu 2 Sr 0.8 1.6:1 —98.2 93.5 Ex. 5 10 2 3.8 Cu 1.8 Sr 0.5 2.15:1  — 97.5 93.0 Fe 0.2 K 0.05*The measurement was not possible.

What is claimed is:
 1. A method of manufacturing a supported catalystcomprising: dissolving salts of metallic components of a catalyst inliquid to form a suspension of particles of the catalyst, the salts ofmetallic components comprising molybdenum, tungsten, and vanadium;precipitating the catalyst particles in the liquid, wherein over 70% ofthe catalyst particles have a particle size of about 10 microns; coatingthe suspension of the catalyst particles to an inert support, whereby acoated support is obtained; and sintering the coated support.
 2. Themethod as defined in claim 1, wherein the catalyst particles arehomogenized by at least one selected from the group consisting of ballmill, attrition mill, dynamo mill, homogenizer, and supersonichomogenizer.
 3. The method as defined in claim 1, wherein thehomogenization of the suspension step is conducted either during orafter the preparation of the suspension.
 4. The method as defined inclaim 1, wherein the salts further comprises salts of metal A and metalB, and wherein A is at least one element selected from the groupconsisting of iron, copper, bismuth, chromium, tin, antimony, nickel,cobalt, manganese, cerium and thallium, and B is at least one elementselected from the group consisting of an alkali metal and an alkaliearth metal.
 5. The method as defined in claim 4, wherein the catalystis represented by a following chemical formula:Mo_(a)W_(b)V_(c)A_(d)B_(e)O_(x), wherein, a, b, c, d, e and xrespectively indicate the atomic ratio for Mo, W, V, A, B and O, whereinwhen a=10, then b=1.5 to 4, c=1 to 5, d=1 to 4, and e=0 to 2 and x isdetermined according to oxidation states of Mo, W, V, A, and B.
 6. Themethod as defined in claim 5, wherein the salts of metal A and metal Bare directly added to the suspension.
 7. The method as defined in claim5, wherein the salts of metal A and metal B are dissolve in liquid toform a solution, and the solution is added to the suspension.
 8. Themethod as defined in claim 5, wherein the molybdate, vanadate andtungstate are dissolved in liquid heated to at least about 90° C.
 9. Themethod as defined in claim 8, wherein the suspension is cooled to atemperature between about 60° C. and about 80° C.
 10. The method asdefined in claim 4, wherein the salts of metal A and metal B are addedto the suspension after dissolving the molybdate, vanadate andtungstate.
 11. The method as defined in claim 1, wherein the supportcomprises at least one selected from the group comprising alundum,silicon carbide, silica, and silica-alumina.
 12. The method as definedin claim 1, wherein the coating of the suspension to the supportcomprises spraying the suspension to the support.
 13. The method asdefined in claim 1, further comprising drying the support applied withthe catalyst particles.
 14. The method as defined in claim 13, whereinthe drying is simultaneously performed with the application of thesuspension to the support.
 15. The method as defined in claim 1, whereinthe catalyst particles are coated to the inert support by one selectedfrom the group consisting of a rotatory sugar coater, a centrifugal flowcoater, and a spherudizer.
 16. The method as defined in claim 1, whereinthe liquid is water.
 17. The method as defined in claim 1, wherein aweight of the liquid is about 0.8 to about 5 times of a weight of thesalts in the suspension.